Venous disease, due to incompetent venous valves, is a prevalent clinical problem. In the U.S., 20 million patients demonstrate chronic venous insufficiency, with swelling, pain, and/or ulceration of the affected extremity. An additional 74 million patients exhibit the dilation and deformity of varicose veins.
Various approaches have been advanced for addressing the clinical problem of poorly functioning venous valves. Mauch et al. (U.S. Pat. No. 7,955,346) teach a percutaneous method for creating venous valves from native vein tissue. Laufer et al. (U.S. Pat. No. 5,810,847) describes catheter placement of a clip appliance onto the cusp of a valve to restore the function of incompetent lower extremity venous valves. Multiple designs for implantable venous valves have also been described. These designs involve implantable prosthetic valves that mimic the patient's natural (autologous) valves; that is, the implants use pliable leaflet or flap valves to restore unidirectional venous flow. Examples of such implantable venous valves are described by Acosta et al. (U.S. Pat. No. 8,246,676), Shaolian et al. (U.S. Pat. No. 6,299,637), and Thompson (U.S. Pat. No. 8,377,115), for example.
In order to mimic native human peripheral venous valves, leaflet or flap valves are formed of extremely thin membrane material, to allow the valve to open properly for return flow to occur in the low pressure venous system, while still providing proper sealing and avoiding valvular insufficiency. Prosthetic membrane or flap valves are prone to failure, due to tearing from repeated opening and closing of the leaflets, permanent closure due to thrombosis and cell adhesion to the prosthetic leaflets, or leaflet inversion and incompetence over time. Currently available replacement venous valves, whether artificial or transplanted tissue valves, also often cause problems with thrombosis or clotting during long term implantation.
Therefore, it would be advantageous to have improved implantable venous valves, which would be designed to address these challenges. It would desirable, for example, to have a prosthetic venous valve that prevents and/or accommodates for the occurrence of thrombosis or cell adhesion to the valve components during chronic valve implantation.